5G and beyond systems are anticipated to provide a variety of service classes with different requirements in terms of latency, reliability and connectivity [1]}, [2]}, [3]}. This naturally raises concerns about their coexistence, especially after it has been shown that allocating a dedicated bandwidth for each service is not spectrally efficient [4]}. In particular, providing a dedicated bandwidth for ultra reliable and low latency communications (URLLC) class of service has been shown to be poorly efficient where the effectively used bandwidth could be less than 5% of the total allocated resource. This is mainly due to URLLC traffic characteristics and requirements [5]}. In fact, the URLLC services come with stringent requirements in terms of latency (less than one millisecond) and reliability (packet error less than \(10^{-6}\) ), implying that such services require immediate availability of spectral resources [6]}, [3]}. Meanwhile, given the sporadic characteristic of URLLC traffic and their short packet size, the allocated resources will only be used occasionally and for a short period [1]}, [2]}, [10]}, [11]}. Therefore, on-demand resource allocation for URLLC transmissions is deemed a promising solution to make good use of spectral resources.
